The subject matter disclosed herein relates to ultrasonic testing, and more particularly, a method and system for ultrasonic testing with a single channel ultrasonic test unit.
Nondestructive testing devices can be used to inspect test objects to detect and analyze anomalies in the objects. Nondestructive testing allows an inspection technician to maneuver a probe on the surface of the test object in order to perform testing of the underlying structure. Nondestructive testing can be particularly useful in some industries, e.g., aerospace, power generation, and oil and gas transport or refining, where inspection of test objects must take place without removal of the object from surrounding structures, and where hidden anomalies can be located that would otherwise not be identifiable through visual inspection. One method of nondestructive testing is ultrasonics.
Generally, an ultrasonic testing system includes an ultrasonic probe for transmitting and receiving ultrasonic acoustic waves to and from a test object, and a probe cable for connecting the ultrasonic probe to an ultrasonic test unit that includes a display for viewing the test results. The ultrasonic test unit can also include power supply components, signal generation circuitry, amplification and processing electronics, and device controls used to adjust the instrument for the inspection. In an ultrasonic testing system, electrical pulses are fed from the ultrasonic test unit to an ultrasonic probe where they are transformed into acoustic pulses by one or more ultrasonic transducers (e.g., piezoelectric elements) in the ultrasonic probe. During operation, electrical pulses are applied to the electrodes of one or more ultrasonic transducers, thus generating ultrasonic acoustic waves that are transmitted to the test object to which the probe is coupled. Conversely, when an ultrasonic acoustic wave is reflected from the test object and contacts the surface of the ultrasonic transducer(s), it causes the transducer(s) to vibrate generating a voltage that is detected as a receive signal by the ultrasonic test unit. As the ultrasonic acoustic waves pass through the test object, various reflections, called echoes, occur as the ultrasonic acoustic wave interacts with anomalies within the test object and with the inner surface (back wall) of the test object.
When testing with a single element probe, the echo signals are typically displayed on the screen of a single channel ultrasonic test unit as an A-scan trace with echo amplitudes appearing as vertical deflections of the trace and time of flight or distance information displayed as horizontal position along the trace. When inspecting a weld, for example, if an echo is identified other than a geometry echo, that echo may indicate the presence of an anomaly in the weld. This single channel probe is often mounted on a wedge to direct the sound at an angle (e.g., from thirty to seventy degrees) to inspect different regions of the test object. In order to inspect the full volume of the object it may be necessary to scan the object several times using different angles (wedges). Inspecting the test object at several different angles can be time consuming.
A phased array ultrasonic probe has a plurality of electrically and acoustically independent ultrasonic transducers mounted in a single housing. By varying the timing of the electrical pulses applied to the ultrasonic transducers, a phased array ultrasonic probe can generate ultrasonic beams at different angles, allowing the phased array ultrasonic probe to steer the ultrasonic beam at different angles (e.g., from thirty to seventy degrees at one degree increments) through the test object to try to detect anomalies. The ultrasonic waves received at the various angles can be processed to produce a sector scan image of the test object, allowing visual identification of any anomalies. While the phased array ultrasonic probe can produce the data necessary to generate a sector scan image, and eliminate the need to rescan the test object several times with different wedges on a single element probe, the phased array ultrasonic testing unit is significantly more expensive that the single channel ultrasonic testing unit. Also, for phased array ultrasonic probes containing dozens of individual elements, the probe cable from the phased array ultrasonic testing unit to the phased array probe can be quite dense and difficult to maneuver.
The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.